Rotary inputs, such as knobs, are common in a multitude of everyday devices. Historically, rotary inputs have been mechanically linked to the component they control. Any indication of the current setting was provided by markings on the housing of the device where the rotary input is installed.
For example, in a conventional analog radio, the volume control includes a knob with alignment markings on the front panel of the radio. When the knob is rotated, alignment of a mark on the knob with one of the marks on the panel indicates the volume setting. In such a configuration, it is obvious to the user of the radio how to increase the volume; typically, clockwise rotation of the knob increases the volume.
The configuration of the rotary input in a conventional digital device may be different than the configuration of an analog device. For example, many conventional digital electronic devices, such as those found in homes, automobiles, and portable devices, include a display for displaying the state of the device. The display includes information corresponding to the position of the rotary input device. In such a device, the knob's location relative to the display provides the user with an indication of which direction to turn the knob to increment a setting. For example, in an automotive radio with a conventional digital display the fader control is typically represented by a bar graph with the front of the car to the left and the rear to the right. The middle of the graph represents an equal balance between the front and rear speakers of the car. The bar graph is typically located above the knob so that by turning the knob clockwise, the signal and the corresponding bar graph is shifted towards the rear of the car. If the spatial relationship between the control and the display is not well designed, the direction that the user is supposed to turn the input may be ambiguous, i.e., the user will be unsure whether to turn the rotary input clockwise or counter clockwise to select the next item in a list.
In one conventional interface design, a virtual knob displayed in the interface provides the user with a visual cue regarding how to move the physical knob located on the console. The physical knob is vertically aligned with and located below the screen and is turned based on the representation shown on the screen, i.e., a clockwise motion implies leftward movement; a counterclockwise motion implies a rightward movement. While this combination provides an intuitive interface, it also requires a large display in order to display both the menu items and the virtual knob. In some sections of the interface, the virtual knob is not displayed. If the knob is placed below (or above) the display, the position of the knob indicates which direction to turn the knob to select form a horizontal list; if the knob is placed beside the display, the position indicates which direction to turn the knob for a vertical list. However, if the knob is placed below (or above) the display, it is unclear in which direction to turn the knob to select from a vertical list. Similarly, if the knob is placed next to the display, it in unclear in which direction to turn the knob to select from a horizontal list.
As electronic devices continue to evolve, the complexity and number of features they include continues to increase. The increase in complexity makes it difficult to place a number of rotary input locations that provide the user with visual cues for how to operate the device. Additionally, the size of the devices and of the displays for providing information and navigational cues to the user continues to decrease. The decrease in size makes it difficult or impossible to provide a virtual knob in the display to provide a visual cue.
Thus a need exists for providing a user with a visual cue for using a rotary input device in complex electronic devices.